fix(sage): remove usage of locally installed balena binary

This override was added in 30ed5e9 to
be able to use balena in NixOS. However, the cost of supporting NixOS is
not worth the issues that arise when everyone potentially runs different
balenacli versions.

This commit removes the check if user already has balena CLI installed,
and will now always use the version specified in this file.

tools/sgbalenacli/tools.go

@@ -54,13 +54,6 @@ func Whoami(ctx context.Context) (WhoamiInfo, error) {
 }
 
 func PrepareCommand(ctx context.Context) error {
-	// Special case: use local balena CLI if available.
-	if binary, err := exec.LookPath("balena"); err == nil {
-		if _, err := sgtool.CreateSymlink(binary); err != nil {
-			return err
-		}
-		return nil
-	}
 	binDir := sg.FromToolsDir(toolName, version)
 	binary := filepath.Join(binDir, toolName, binaryName)
 	hostOS := runtime.GOOS